Serum or plasma electrolytes panel with specific ion measurements (including sodium, potassium, chloride, bicarbonate, and possibly calcium)
This test measures key minerals and chemicals in your blood that help regulate important body functions, such as fluid balance and nerve signaling.
["Your blood chemistry helps doctors understand how well your organs are working and detect imbalances early."]
Key facts at a glance
- LOINC
- 11851-3
- Short code
- Fet Head OFD US.meas
- Synonyms
- Fet Head OFD US.meas
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- us-measured
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What This Test Measures
This panel typically includes measurements for sodium (Na⁺), potassium (K⁺), chloride (Cl⁻), and bicarbonate (HCO₃⁻), which are essential electrolytes. Some versions may also assess calcium levels. These substances help maintain fluid balance, nerve function, and muscle contractions.
Why It’s Ordered
Doctors may order this test to evaluate dehydration, kidney function, heart conditions, acid-base balance, or electrolyte imbalances. It’s often used in emergency settings or when monitoring chronic illnesses like diabetes or kidney disease.
Common Reasons for Testing
Common triggers include symptoms like excessive thirst, confusion, irregular heartbeat, muscle weakness, or unexplained fatigue. It may also be part of routine check-ups for high-risk patients or those on medications that affect electrolytes.
Sample Collection and Preparation
A blood sample is drawn from a vein, usually in your arm. The blood is processed to separate serum or plasma (the liquid part) for testing. No special preparation is needed, but fasting may be required for some related tests.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Low sodium levels (hyponatremia) can cause headaches, nausea, or confusion, while high sodium levels (hypernatremia) may lead to weakness or seizures. Potassium imbalances can affect heart rhythm, while bicarbonate levels help diagnose acid-base disorders like metabolic acidosis or alkalosis.
How long does it take to get results? Results are typically available within 24 to 48 hours, depending on lab processing times and urgency.
Is there any risk or discomfort with this test? There’s minimal discomfort from the needle, but some people experience bruising or slight pain. Rarely, allergic reactions can occur.
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy